RE: [RESEND PATCH v2] devres: Really align data field to unsigned long long

[David Laight]

From: Alexey Brodkin
> Sent: 09 July 2018 11:00
...
> That's a good idea indeed but it doesn't solve the problem with
> struct devres_node. Consider the following snippet:
> -------------------------------->8-------------------------------
> 	struct mystruct {
> 		atomic64_t myvar;
> 	}
> 
> 	struct mystruct *p;
> 	p = devm_kzalloc(dev, sizeof(*p), GFP_KERNEL);
> -------------------------------->8-------------------------------
> 
> Here myvar address will match address of "data" member of struct devres_node.
> So if "data" is has offset of 12 bytes from the beginning of a page then
> myvar won't be 64-bit aligned regardless of myvar's attribute, right?
...
> > > -	unsigned long long		data[];	/* guarantee ull alignment */

Ahh, that line should be:
	u8 data[] __aligned(8); /* Guarantee 64bit alignment */

	David